Breakthrough in Semiconductor Laser Tech

Zinc-Oxide NanoWires Could Mean Better DVDs, Virus Killers

A breakthrough in semiconductor laser technology could potentially lead to a new way to kill viruses and increase the storage capacity of DVDs.

Researchers from the University of California at Riverside in collaboration with a team from the University of Central Florida have figured out a way to increase the use of ultraviolet semiconductor diode lasers. These tiny lasers, less than the width of a hair strand, are already widely used in data processing, information storage and biology.

Their applications have been limited, however, by size, cost and power. The current generation of ultraviolet lasers is based on a material called gallium nitride. UC Riverside’s Jianlin Liu, a professor of electrical engineering, and his colleagues have made a breakthrough in zinc oxide nanowire waveguide lasers, which can offer smaller sizes, lower costs, higher powers and shorter wavelengths.

Leonid Chernyak, a UCF professor of physics and Yuqing Lin, a graduate student at UCF, are collaborators on the research, which is published in this month’s issue of Nature Nanotechnology.

Until now, zinc oxide nanowires couldn’t be used in real-world light emission applications because of the lack of p-type, or positive type, material needed by all semiconductors. Liu solved that problem by doping the zinc oxide nanowires with antimony, a metalloid element, to create the p-type material.

The UCF researchers conducted experiments to verify that the zinc oxide nanowires in the study had the necessary properties for conductivity. Chernyak and Lin used UCF’s unique Scanning Electron Microscope probe station for the work. Chernyak designed and built the state-of-the-art station.

“We are so excited about this new development,” Chernyak said. “This research is most promising. While more research is needed, this may give us more options to explore, which could have some significant impacts on our daily lives from how we store our data to medical therapies that could help treat disease.”

For information storage, the zinc oxide nanowire lasers could be used to read and process much denser data on storage media. For example, a DVD that would store two hours of music could store four or six hours using the new type of laser.

For medical therapies, the ultra-small light beam from a nanowire laser can penetrate a living cell, or excite or change its function from a bad cell to a good cell. The light could also be used to purify drinking water.

For photonics, a field in which researchers study and create high-powered lasers for many applications, including medical and military, the ultraviolet light could provide even faster data processing and transmission. Reliable small ultraviolet semiconductor diode lasers may help develop ultraviolet wireless communication technology, which is potentially better than state-of-the-art infrared communication technologies used in various electronic information systems.

This is a giant move forward, but more work needs to be done with the stability and reliability of the p-type material, Liu said.

“People in the zinc oxide research community throughout the world have been trying hard to achieve this for the past decade,” Liu said. “This discovery is likely to stimulate the whole field to push the technology further.”

The work on the ZnO device was in part supported by Army Research Office Young Investigator Program and the National Science Foundation. The work on p-type ZnO was supported by the Department of Energy.

Co-authors of the study are: Sheng Chu, Guoping Wang, Jieying Kong, Lin Li and Jingjian Ren, all graduate students at UC Riverside; Weihang Zhou, a student at Fudan University in China; Jianze Zhao, a visiting student from Dalian University of Technology in China and the UCF professor and student. (source news.ucf.edu)

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